1. Field of the Invention
The present invention relates to an apparatus for trimming an outer layer of fat off a piece of meat, in particular but not exclusively the back fat of a pork loin. The loin is conveyed between the top surface of a conveyor and a set of endless chains, and is passed through a blade to trim off the fat.
2. Brief Description of the Prior Art
Canadian patent No. 1,079,114 (Van Heyningen) issued on June 10, 1980, describes an apparatus of the above type for trimming the back fat from pork loins. The apparatus of Van Heyningen comprises (a) a conveyor with a top surface formed of a plurality of arcuate slats, (b) a pair of endless chains above the conveyor, and (c) an arcuate knife blade separated from the top surface of the conveyor by a distance which is adjustable in function of the thickness of the back fat. The chains and the slats are respectively provided with teeth and points capable to penetrate the loin.
In operation, the pork loin is placed on the upstream end of the conveyor centrally of the arcuate slats, and the conveyor and the endless chains are driven in the same direction at substantially the same linear speed. As the loin is conveyed toward the knife blade, the teeth of the chains and the points of the conveyor penetrate the meat to force it across the blade and thereby separate the fat and lean portions.
A first drawback of the apparatus of Van Heyningen is that the conveyor and the chains are operating at the same linear speed An adequate compression and tension distribution in the loin to facilitate passage thereof across the blade is accordingly not produced.
Another drawback of the apparatus of Canadian patent No. 1,079,114 is that the loin must be placed initially centrally of the conveyor; the apparatus cannot automatically adjust the lateral position of the pork loin as the penetrating teeth and points maintain it in its initial position.
In this prior art apparatus, the knife blade cannot be lowered very close to the top surface of the conveyor to trim off very thin layers of back fat. Indeed, the minimum distance between the knife blade and the conveyor is determined by the height of the points penetrating the loin. Therefore, the apparatus of Van Heyningen further presents the disadvantage of causing a loss of meat when the layer of fat is thin.